In one particular application, the distribution system is intended to equip bottles used in perfumery, cosmetics or for pharmaceutical treatments. As a matter of fact, this type of bottle contains a liquid which is delivered under pressure by a manually operated pump or valve by means of a push-button which is designed to enable spraying of the liquid.
Such push-buttons are conventionally made in two parts: an operating body and a spray nozzle that are combined together to form the push-button. In particular, the spray nozzle can be designed so as to form an aerosol with the liquid, in particular by defining a so-called vortex chamber.
To accomplish this, the vortex chamber is designed to make the liquid spin very rapidly so as to give it speed. Thus, by providing for the vortex chamber to be extended at the centre thereof via a distribution opening, the liquid can escape at high speed while fractionating itself into fine droplets forming the aerosol.
However, since this fractionation occurs in an uncontrolled manner, the aerosol consists of droplets of widely varied sizes. For example, for a pump or a valve supplying a push-button with a stream of alcohol under a pressure of 5 bars, and a 0.3-mm outlet opening, the aerosol commonly consists of droplets having a diameter of between 5 μm and 300 μm.
Such being the case, the large droplets are heavier than the smaller ones and follow a different distribution path, and are capable of causing indelible stains in the case of perfumes. Therefore, the small droplets are the lightest ones and can be inhaled, which may be the desired objective in the case of medications, but which can have an undesirable effect in the case of toxic products. Furthermore, in the case of medications which must be dispensed according to a precise dosage regimen, the location of application, e.g. inside the respiratory system, depends on the size of the droplets, and the large disparity in sizes distorts the treatment.
Furthermore, the size of the droplets derived from a vortex chamber depends in part on the force and speed with which the user operates the pump by pressing on the push-button with his finger, because the pressure induced depends on it.
Furthermore, and in particular because of the effects of the centrifugal force at the outlet of the vortex chamber, the aerosol has a tendency to be hollow with a substantially conical envelope which consists of the majority of the droplets, while there are few of same on the inside of the cone. In particular, this distribution of the droplets can be harmful in the case of dermal applications.
In order to solve the aforementioned problems, in particular the document FR-2 903 328 proposes to use a non-vortex nozzle which is provided with a micro-screen to ensure the calibration and spatial distribution of the droplets.
However, this embodiment necessitates flow areas through the micro-screen which are extremely small, in particular of the order of 6 μm in diameter, which requires fine filtration of the liquid in order to avoid clogging problems. Furthermore, the difficulty of producing and assembling these micro-screens in the body remains considerable.
A push-button is also known, in particular from the document FR-2 915 470, which includes a distribution chamber which is provided with channels each converging towards an outlet opening, said convergent channels being designed to enable the impaction of the liquid jets dispensed by said openings. Thus, during the impaction of the jets dispensed at high speed, an aerosol is formed, without the use of a vortex chamber.
In order to supply the convergent channels with liquid, the prior art proposes to equip the distribution chamber with an annular channel from which said convergent channels extend. This solution enables distribution of the streams of liquid introduced into each channel but poses a certain number of problems.
In particular, the liquid introduced into the annular channel under pressure becomes turbulent, which does not enable the streams of liquid introduced into the convergent channels to be stabilised. Furthermore, the speed of the liquid stream introduced remains low, which, while limiting the impaction energy of the liquid jets dispensed, does not enable an aerosol of optimum quality to be produced, in particular with respect to the fineness, calibration and spatial distribution of the droplets comprised in the same.
In addition, the supplying of the convergent channels according to the prior art does not enable fractionation of the dose of liquid to be dispensed, i.e. delivery of only a portion of the dose provided by the pump. As a matter of fact, the bearing-down stroke of the push-button is carried out too quickly, in particular of the order of 0.2 second for 100 μl, in order to be capable of being interrupted by the user.
The invention aims to solve the problems of the prior art, in particular by proposing a push-button which enables the dispensing of an aerosol formed of droplets having improved calibration and spatial distribution, and does so while increasing the production time for said aerosol.